Laboratory 4 Zoology 1114
Phylum Platyhelminthes
Quiz
Scientific Papers - see appendix D before class and goto webct
1. Phylum Platyhelminthes
- Name trans. To “flatworm”, which is common name
- difference between this phylum and cnidarians is tissue layers
1. Cnidarians (diploblastic)
a. epiderm
b. endoderm
2. Platyhelminthes (triploblastic)
a. epiderm (special name
ectoderm)
b. mesoderm
c. endoderm
2. Animal Body Plans
- difference again between
Cnidarians and Platy’s
1. Cnidarians
a. Body Symmetry
- radially symmetrical
b. Body Plans – 3 forms
1. Polyp
2. Medusa
3. Polymorph
2. All others
a. Body Symmetry –all others [except echinodermata]
- bilaterally symmetrical
- There is only one way to cut it that could be made that would produce
a mirror image.
- Creates different planes [Nekker Cube example]
1. anterior – posterior
2. dorsal – ventral
3. lateral
- Anterior portion becomes concentration of nervous tissue
- Called “cephalization”
b. Body Plans
1. Acoelomate –the platy’s
2. Pseudocoelomate – we get to these later
3. Eucoelomate
Body Plans
1. Acoelomate – pronounced “a-seal-o-mate”
- “without a cavity”
- coelom : body cavity that
lies between the gut and body wall
- in this group, cavity
is filled with mesodermal tissue
2. Pseudocoelomate –
- “false cavity”
- body cavity is lined with
both mesodermal and endodermal layers
- there is space between
endoderm and mesoderm
3. Eucoelomate – “true cavity”
- cavity lined only with
mesoderm
- think, just like an acoelomate
body form but the mesoderm then splits/opens up and leaves a cavity surrounded
completely by mesoderm
4. Phylogenetic evolution
- Flatworms of class Turbellaria came first then others with class
Cestoda being last and most complex
Phylum Characteristics
1. Acoelomate
2. Bilateral Symmetry
3. Triploblastic
4. Dorsoventral flattening
5. Specialized organ systems
6. Unsegmented [1 ribbon-like but not truly segemented]
Minor
1. Cephalization
2. Incomplete GVC –only 1 opening
3. Protonephridia
4. Hermaphrodite – posses both m/f organs
- Monoecious – “one house”
- technical name for hermaphrodite found in literature
- Meiosis with self – technical
name for this is “colonial cross”
5. Mostly parasitic
Class Characteristics
1. External parasite with anterior mouth & 1 host cycle
.. . . . . . . . . . . .Class Monogenea
2. Internal parasite with anterior mouth & 2 host
cycle . . . . . . . . . . . . .Class Trematoda
3. Internal parasite, ribbon-like, no mouth . . . . . . . .
. . . . . . . . . . . . . . . . . .Class Cestoda
4. Free-living, flat with ventral mouth . . . . . . . . . .
. . . . . . . . . . . . . . . . .Class Turbellaria
Class Monogenea
1. Common name: Flukes
2. External parasite
3. 1 host…dog to humans
4. Skip this
Class Trematoda
1. internal parasites
2. Two host cycle
Ex.1) Sheep to snails to
humans – sheep liver fluke is common name
Ex2.) Snail to fish muscle
to humans – Chinese liver fluke is common name
Ex3.) Snail to water chestnut
to humans – Fasciolopsis is common name
3. Tegument – extra tough epidermal layer… antigen evading techniques
[modern pharmaceutics researching this]
4. 1 sucker, no ventral moth
5. Monoecious
Class Cestoda
1. internal parasite – 2 host
2. ribbon-like , makes it look segmented (actually called “strobilated”)
3. Tapeworm is common name
4. No GVC like others b/c super specialized – exchange across tegument
5. Cells separated by membranes in syncitial [sin-sish-e-al]
6. Scolex – pronounced “skoal-lex”
7. Each ribbon segment called a “proglottid”
8. Pregnant proglottid – section colonial crosses then drops off through
feces to infect another host through
snail [2 things: perpetuates
species but avoids competition for resources]
9. Competes for food with host
Class Turbellaria
1. Free living common genus we study is Dugesia.
2. Covered with ciliated epidermis
3. Mouth located ventral and posterior with a pharynx
- Pharynx is a type
of esophagus that in this case can be extended out through the mouth
like a straw to take
up nutrients or get rid of wastes through environment
4. Monoecious –1 house m/f in one
-Compare with Dioecios –2
distinct bodies with 1 sex housed per
5. Binary fission as well
6. Digestive system
- highly branched but all
connected to a main pipe (GVC)
- extracellular digestion
then internal [aka, intracellular digestion]
- GVC lined with cilia to
help distribute food throughout
- 1 way GVC
8. Excretory System
- 1st group to have a system
for waste elimination [nitrogen from a.a.]
- look back and compare
to Protista, sponges, and hydras
- Network of tubules in
mesodermal layer. 1 way pump
- Flame cell – have flagella
that pump water into duct
- Protonephridia
9. Reproductive system
- Monoecious
- Has testes and ovaries
with internal fertilization [remember hydra was external fertilization]
- Also asexually , especially
in regeneration
- Animal development example
10. Nervous System
- Ladder-like nervous system
with cephalization located laterally and ventrally
- Anterior brain, first
time we use this word
- Sensory neurons: remember
pathway
- Sensory input – brain
– motor output
- Afferent – towards ; efferent
- away
- Sense organs
a. eye-spots - photons
b. auricles – chemicals/ligands
Nerve Cell Specialization
1. Neuron types
a. General Form: dendrite
– cell body – axon
2. Neuron Pathway
a. 1 axon to motor output
- Sensory neuron – effector muscle
b. 1 axon to more than 1
motor output
- Sensory neuron – synapse – interneuron (branching axon) – 2 effector
muscles
3. Synapse release chemical between pre- and post synaptic cleft (remember
ligand discussion)
4. Specialized Sensory Cell types – not necessarily neurons
a. Mechanoreceptors – deformations
to cell
- Posture, gravity orientation (i.e., up/down), physical stimuli
b. Chemoreceptors – ligand
mediated
- Gustatory and olfaction
c. Photoreceptors – photons
(light-waves) stimulate cell
Classical Conditioning
a. Pavlov – bell sounds
and dog salivated
b. Pairings of one stimulus
to another
1. Controlled Stimulus [CS] – something not normally in environment
2. Uncontrolled Stimulus [US] – something normal to them
- dog – normally salivates
- planaria - normally escape
c. CS becomes a predictor
[key word] of the US
d. Elicits an Conditioned
Response [CR]
Labs
1. Class Slides
-Identify as many items
from book as possible
2.Lab Exercise with Planaria
4 Different Tests
1. Response to light –flash a light on it
a. Direct illumination – watch reaction
b. Background pattern – see where it’d go
2. Response to touch – pin-prick and watch it move
a. intact animal
b. anterior half
c. posterior half
3. Response to chemicals – add liver
a. Draw how moves (zigzag)
4. Classical Conditioning – learning paradigm – 100 CS-US pairings
a. extinction response after CS alone
Statistics
Chi-square
1. Null hypothesis important here
2. Test differences between or among different groups
X2 = Sum [(observed – expected)2 ]
Expected dF= 2 - 1 = 1 (b/c 2 groups black/white)
Ex.) Sample Data
OBS EXP
Black White Black White
4 0 2 2
4 0 2 2
4 1 2.5 2.5
BLACK
X 2 = (12-6.5)2/6.5 = 4.65
WHITE
X2 = (1-6.5)2 / 6.5 = 4.65
total = 4.65 + 4.65 = 9.3 - use this number
in chi-square box
IMPORTANT TERMS:
Phylum Platyhelminthes
Class Turbellaria
Class Trematoda
Class Cestoda
triploblasty
(ectoderm, endoderm, mesoderm -- epidermis, gastrodermis, mesoderm)
acoelomate
pseudocoelomate
eucoelomate
bilateral symmetry
cephalization
eyespot
auricle
gastrovascular cavity
pharynx
lateral nervecord
ovary
testis
flame cells
sense organs
axons
dendrites
effector
synapse
photoreceptor cell
chemoreceptor cell,
mechanoreceptor cell.